High Bacterial Inoculum Research Articles

Use of an in-vitro kinetic model to study antibiotic combinations.

A two compartment pharmacokinetic model was used to study combinations of piperacillin with N-formimidoyl thienamycin or amikacin, and azlocillin with netilmicin against strains of Pseudomonas aeruginosa. Antibiotic antagonism seen with in-vitro static tests of piperacillin and thienamycin did not occur with the kinetic model. Piperacillin plus amikacin showed enhanced activity, and azlocillin prevented bacterial regrowth seen with netilmicin alone during multiple dosing experiments at high bacterial inocula. This model is useful in the study of antibiotic combinations.

Risikofaktoren bei eitriger Meningitis im Kindesalter

Retrospective studies of the case histories of 237 children suffering from bacterial meningitis at the department of pediatrics, university of Graz, show the significant difference between cured, deceased and children with permanent sequels. The risk factors for the fatal outcome of meningitis were: age (less than 1 year), bacteria (pneumococcus), concomitant disease (pneumonia), low initial white cell count in the blood (less than or equal to 5000/cmm) as well as in cerebrospinal fluid (less than or equal to 4000/cmm), high cerebrospinal fluid protein (greater than or equal to 336 mg%) and a high bacterial inoculum (greater than or equal to 10(7) CFU/cmm). With all these risk factors at the time of diagnosis of purulent meningitis the chance for recovery is poor.

Meningitis Due to Haemophilus influenzae Type b Resistant to Both Ampicillin and Chloramphenicol

A strain of Haemophilus influenzae type b with considerable resistant to both ampicillin and chloramphenicol was recovered from a South Dakota child with meningitis. There was an initial lack of response to conventional doses but the child improved after a brief period of 200 mg/kg/day of chloramphenicol. The organism showed in vitro resistance to ampicillin, carbenicillin, tetracycline, and chloramphenicol (for each antibiotic the minimal inhibitory concentration (MIC) was 8 micrograms/ml or greater with a bacterial challenge of 10(5) colony-forming units (CFU)/ml), but it was sensitive to both streptomycin and rifampin (MIC 1.6 micrograms/ml, respectively). Isobolograms constructed from the results of testing various concentrations of ampicillin and chloramphenicol showed additive effects with high bacterial inocula (10(5) or 10(7) CFU/ml), but antagonism with low inocula (10(2) or 10(4) CFU/ml).